Going to Rebuild 400E Power Steering Pump.
 

Finally I had enough leakage from the P/S pump, the puddle on the garage floor drives me crazy, what makes me feel worse is there are two Lexus (GS400&GS300) sit beside my 400E, they must be laughing at my Mercedes everyday they see the puddle.

I received the P/S pump repair kits from Partshop, and going to rebuild it soon, I have the repair CDs, but I'd like to get some suggestions from someone who did this before.

What I got was 10 O-rings and gaskets, It will take quite a long time for me to figure out where I should put them, I then guess I have to remove the pump from car and do it very carefully.

Before I detach the pump, how can I drain the P/S fluid? how long should I prepare for this task? also any tricks will be appreciated.

Hey man, its easy. Just take your time and match the old O rings to the new ones one at a time. Im not familiar with the exact pump used on your model but I suspect that they are very similar to mine.

Drain the fluid out of the pump as best you can with a suction device such as a turkey baster. Remove the return line and any excess fluid will drain out of the reservoir. Cleanliness is very important. Take the pump to a clean well lit area to work on it. As you remove parts, remember the sequence so you can get it back together again. As you reveal O rings replace them after carefull comparison to the new ones. You will probably not use all the new parts as they often have several models that covered by the rebuild kits.

Not too much to it. Good luck.

Finally was able to start the rebuild during the Christmas holiday.

To my surprise, after I removed distributor cover, intake hose, drive belt and power steering pump pulley, I found the place fluid leaked from right away, it was not the power steering pump that leaks, it was just the short hose that connected the power steering fluid reservoir and pump, the lower clamp that fastened the hose to the pump was so loose that I could tighten the bolt 5-6 turns, didn't know how that could happen, maybe the person who did the repair job forgot to tighten it?

Though I was just a step away from removing the whole power steering pump, (all hex bolts and a 6 mm Allen screw exposed), I was too lazy to go ahead. To test the result, I put a white paper underneath the car, and left it over night, after a whole day, it didn't leak a drop! before it leaked 3-4 drops a night, that was a easy fix, I have to save the P/S kit for the feature then.